The overall goal of this study is to determine whether test meal size with the 13-C-octanoate breath test (OBT) to measure gastric emptying influences the ability to distinguish between subjects with normal and delayed gastric emptying This study is funded through an NIH Small Business Innovation Research grant with Metabolic Solutions. A minor objective is to determine if the cutaneous electrogastrogram (EGG) varies with test meal size and to determine the correlation of the EGG with gastric emptying as assessed with simultaneous EGG/OBT.